STERIC ACCELERATION OF INTRAMOLECULAR OXIME AND HYDRAZONE CYCLOADDITIONS

Selected Conformational constraints, achieved by the incorporation of ortho-substituents in 2-substituted 1-allyloxybenzenes, where the subs tituent is a 1,3-dipole or its tautomeric precursor, as in oximes, can be employed to accelerate the 1,3-dipolar cycloaddition process. Some evidence that hydrazones preferentially react with the alkene group b y prior oxidation to the corresponding nitrilimine species is presente d.